Underlying mechanisms of memory will be investigated in two standard laboratory species, rhesus monkeys (6) and pigeons (18), which have demonstrated their ability to accurately perform list-memory tasks and are well suited to this memory research. Interference has been demonstrated to be a (the) major determinant of memory. Interference will be manipulated in single-item (same/different) memory tasks to determine how interference from previous trials degrades memory and how subjects develop memory strategies to deal effectively with this interference. Among the manipulations will be: stimulus (pictures) set size (for interference), locus of interference, observing responses (for attention), memory retention delay (0-20s for pigeons, 0-30s for monkeys), and trial spacing. New tests have been developed to measure the effect of interference and explore whether subjects' learn to deal more effectively with this interference. These results will bear upon the issues of familiarity/automatic versus identity/controlled memory processing in animals. Subjects will then be trained and tested in multiple-item list memory tasks (1-4 items). Similar manipulations will investigate how interference from previous lists determines the shape of the serial position function. Other manipulations (item presentation time, time between items, number of list items) will investigate how interference among list items determines the shape of the serial position function. These results should reveal which aspects of interference are under strategic subject control and which aspects are fixed and automatic. Findings should bear upon general processes of visual memory that are shared among such diverse species as avians and primates. [unreadable] [unreadable]